Rebekah Brooks’s former PA Cheryl Carter faces a charge of conspiring to conceal material from the police. Photograph: David Thompson/Rex Features

Rebekah Brooks and her former personal assistant Cheryl Carter must "stand or fall together" the jury in the phone-hacking trial has been told.

The jury of eight women and three men were told by Carter's defence counsel to "park" all previous evidence they had heard on allegations of phone hacking and payment to public officials and to consider, in isolation, the one charge the former secretary faces.

Trevor Burke QC, told the jury they would have to find Carter and Brooks either guilty or innocent together because they have been charged with conspiring to conceal material from police investigating activities at News International in July 2011.

"You cannot convict one of them and acquit the other –- the law does not permit that. The long and the short of it is Rebekah and Cheryl stand or fall together."

Burke told the jury it was important to understand what the prosecution were alleging was a conspiracy and this by its nature involved more than one person.

"You cannot conspire on your own. A conspiracy requires a minimum of two people," he said in his opening remarks.

Burke asked the jury to "bear in mind throughout, Rebekah Brooks has consistently denied her part in this essential two-part conspiracy."

He told them that Brooks and Carter "adore each other" and stood "shoulder to shoulder for 16 years" and that the families of the ex-PA and former chief executive of News International were close.